Plate type heat exchanger

ABSTRACT

The present invention relates to a plate type heat exchanger having a heat exchange element composed of two plates for exchanging heat between a fluid flowing inside the heat exchange element and a fluid flowing outside the heat exchange element. In the plate type heat exchanger, the two plates ( 1 ) have a plurality of depressions ( 8 ), and the depressions are brought into contact with and bonded to each other. Peripheral portions of the plates are sealed to form a space in which a fluid flows and constitute a heat exchange element ( 2 ) having opening portions ( 5, 6 ) at both ends thereof. The heat exchange elements ( 2 ) are piled on and bonded to each other so that the opening portions ( 5, 6 ) communicate with each other.

TECHNICAL FIELD

The present invention relates to a plate type heat exchanger, and moreparticularly to a plate type heat exchanger for exchanging heat betweentwo fluids flowing alternately through adjacent fluid passages betweenpiled plates, which is suitable for such cases where at least one of thefluids flows as a liquid film on a surface of the plate, or is alow-pressure vapor, as an evaporator in a refrigerating machine, or anevaporator or a low-temperature regenerator in an absorptionrefrigerating machine.

BACKGROUND ART

A conventional plate type heat exchanger is of a small size for a heatload, and can cope with an increased heat load by increasing the numberof piled plates having the same shape, so that the plate type heatexchanger is frequently used as a heat exchanger.

The conventional plate type heat exchanger is shown in FIG. 16. As shownin FIG. 16, two plates 1, 1′ having opening portions 5, 6 at both endsthereof are piled on each other so as to form a space R1 therebetween,and peripheral portions of the plates are sealed to form a heat exchangeelement 2. The heat exchange elements 2 are piled on and bonded to eachother in such a state that the opening portions 5, 6 communicate witheach other, thereby forming a heat exchange structure. This heatexchange structure is housed in a shell, and fluids flow inside andoutside the heat exchange elements 2 so as to exchange heat with eachother. A corrugated or fin-shaped plate 42 is mounted within the spaceR1 in the heat exchange element 2 to increase the strength of the platesand promote heat exchange by turbulence of a flow. The upper and loweropening portions 5, 6 are projected in a cylindrical form so as to befitted to each other.

In this type of heat exchanger, an inlet and an outlet for a first fluidpassing through the shell are connected to the opening portions 5, 6.The first fluid flows in parallel through the respective heat exchangeelements 2 as indicated by arrows. On the other hand, a second fluidflows from an inlet and an outlet for the second fluid, which areprovided in the shell, into a space R2 formed outside the heat exchangeelements 2. The outside space R2 can be made wider than the inside spaceR1. Therefore, when a fluid involving a phase change is used as thesecond fluid, the heat exchanger can cope with a volume change inaccordance with the phase change. Further, the inlet and outlet for theoutside space R2 can be made larger than the inlet and outlet for R1.Therefore, the heat exchanger can cope with a fluid that is alow-pressure vapor having a large specific volume. The outside space R2can be made wider than the inside space R1 depending upon the shapes ofprojections and depressions of the plates, so that the heat exchangercan cope with even a lower-pressure vapor.

To manufacture such a heat exchanger, the turbulence plate. 42 ismounted and positioned on the upper plate 1. Then, the lower plate 1′ isplaced on the turbulence plate 42, and the peripheral portion of thelower plate 1′ is folded to be bonded to the upper plate 1, for therebyforming the heat exchange element 2. Next, the adjacent heat exchangeelements 2 are connected to each other so that cylindrical communicatingportions 7 are fitted to each other, for thereby assembling a heatexchange structure. The resulting heat exchange structure isincorporated into a shell 9.

Such a conventional plate type heat exchanger requires three componentsfor constituting the heat exchange element 2, and thus involves problemsthat manufacture and management of the components are burdensome andcostly.

FIG. 17 is an exploded perspective view of a plate type heat exchangerin which a plurality of heat exchange elements 2 are piled on each otherand housed within a shell 9.

With a plate type heat exchanger having a structure shown in FIG. 17,when the number of the heat exchange elements 2 is increased, heatexchange capacity can be improved. Further, a liquid having a largespecific volume, such as a vapor or a vapor-liquid two phase fluid, canbe used as an external fluid. In FIG. 17, the reference numeral 3denotes an opening portion constituting an introduction passage for anexternal fluid, the reference numeral 4 an opening portion constitutinga discharge passage for the external fluid, the reference numeral 5 anopening portion constituting an introduction passage (supply passage)for an internal fluid, the reference numeral 6 an opening portionconstituting a discharge passage (supply passage) for the internalfluid, and the reference numeral 7 a cylindrical communicating portion.

It has been known that when the plate type heat exchanger having thestructure shown in FIG. 17 is used in an absorber or an evaporator of anabsorption refrigerating machine, for example, the refrigerating machinecan be downsized.

In these heat exchangers, since an internal fluid is generally suppliedto a plurality of plates, as shown in FIG. 17, the heat exchanger isused in such a state that an inlet and outlet of the heat exchanger andan inlet and outlet (ports) of the plates are connected to each other,and the ports of the plates are connected to each other, via supplypassages such as supply pipes, discharge pipes, and communication pipesfor a working fluid. In many cases, the supply passages are provided onheat transfer surfaces of the plates because of productivity in such amanner that the supply passages are faced to and communicate with eachother when the plates are piled on each other.

In this case, when the flow rate of the internal fluid is increased, itis necessary to thicken the supply passages 5, 6. Therefore, the supplypassages provided on the heat transfer surfaces occupy the heat transferarea, and simultaneously prevent a flow of the external fluid.

Particularly, as shown in FIG. 18, in such cases where the externalfluid flows as a liquid film for performing heat exchange, as anabsorber or an evaporator in an absorption refrigerating machine, ifwide supply passages are provided, then it is difficult to supply thefluid to entire regions below the supply passages and hence the regionsare not effectively used as the heat transfer surface in many cases. InFIG. 18, a hatched area represents regions of the flow of the fluid, andportions a below the supply passage 5, 6 without hatching representregions of no fluid flowing.

Generally, in the plates, there is provided a fluid distribution portionhaving radial passages for uniformly distributing the fluid suppliedfrom the ports to the plates. As the supply passage becomes wider, thefluid distribution portion becomes more complicated and larger, so thatthe fluid distribution portion occupys a larger area of the heattransfer surface.

Even if supply passages having an elliptic or rectangular shape are usedto solve the above drawbacks, such supply passages increase cost andmake productivity worse. Besides, a flow in a direction of the minoraxis of the shape of the supply passage is worsened, although a flow ina direction of the major axis can be improved. This is not a solution tothe problems.

DISCLOSURE OF INVENTION

The present invention has been made in view of the above drawbacks. Itis therefore an object of the present invention to provide a plate typeheat exchanger having a highly efficient function of heat exchange,which requires a small number of components and can reduce cost ofproduction and assembly.

It is another object of the present invention to provide a plate typeheat exchanger having a highly efficient function of heat exchange,which can be manufactured by a small man-hour and is likely not toprevent a flow of a working fluid even at a high flow rate.

To attain the above objects, according to a first aspect of the presentinvention, there is provided a plate type heat exchanger having a heatexchange element composed of two plates for exchanging heat between afluid flowing inside the heat exchange element and a fluid flowingoutside the heat exchange element, characterized in that: the two plateshave a plurality of depressions, and the depressions are brought intocontact with and bonded to each other; peripheral portions of the platesare sealed to form a space in which a fluid flows and constitute a heatexchange element having opening portions at both ends thereof; and theheat exchange elements are piled on and bonded to each other so that theopening portions communicate with each other.

In the plate type heat exchanger, it is desirable that the depressionsof the plate are formed in a circular shape or a horizontally elongatedelliptic shape, and a contacting portion between projections produced bythe depressions has a plane surface of at least 0.3 mm in width.

The peripheral portions of the two plates may be brought into contactwith each other along whole peripheries upon piling, and contactingportions between the peripheral portions may be sealing by bonding. Atleast one of the opening portions at both ends of the plate may becomposed of a plurality of opening portions.

According to a second aspect of the present invention, there is provideda plate type heat with opening portions at both ends thereof are piledas a set on each other to constitute a heat exchange element, aplurality of the heat exchange elements are piled on each other to forma space between the two plates constituting the respective heat exchangeelements as a passage for a first fluid, and a space between theadjacent heat exchange elements as a passage for a second fluid in heatexchange relationship with the first fluid, and the plate serves as aheat transfer surface for both of the fluids, characterized in that: oneof the plates has a contacting portion with the other plate at aperipheral portion of the plate and at the opening portion; when the twoplates are piled as a set on each other, only the peripheral portions ofthe plates are brought into contact with each other; when the plates arepressed by an applied force until the projections and depressions of thetwo plates are brought into contact with each other, the contactingportions of the peripheral portions deform to be brought into surfacecontact with each other along whole peripheries; when the adjacent heatexchange elements are piled on each other in such a manner that theopening portions are aligned with each other, only the peripheralportions of the opening portions are brought into contact with eachother; and when the plates are pressed by an applied force until theprojections and depressions of the plates of the heat exchange elementsare brought into contact with each other, the contacting portion of therespective peripheral portions of the opening portions deform to bebrought into surface contact with each other along whole peripheries.

In the plate type heat exchanger, it is desirable that all of the platesare integrated by brazing the contacting portions at the peripheralportion and at the opening portions of the plates. The projections anddepressions of the plate may be formed in a shape inclined to onedirection. The projections and depressions of the plate may be formed asspot-like projections and depressions having a circular or other crosssection, and the height of the projections may be larger than the depthof the depressions when the heat exchange element is constituted.

Further, it is desirable that the plate has a rising portion so that therising portion is fitted into the opening portion of another plate whenthe plates are piled on each other.

According to a third aspect of the present invention, there is provideda plate type heat exchanger having a plurality of hollow plates in ashell, each of the hollow plates composed of two thin sheets and havingan internal space enclosed at an outer peripheral portion thereof, anintroduction passage and a discharge passage for allowing an internalfluid to flow inside the plates being connected to the plates, anintroduction passage and a discharge passage for allowing an externalfluid to flow within a space between the outside of the plates and theshell being connected to the shell, characterized in that: at least oneof the introduction passage and the discharge passage for the internalfluid connected to each of the plates is composed of a plurality ofpassages.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are schematic views showing a whole structure of a platetype heat exchanger according to a first embodiment of the presentinvention, and FIG. 1A is a front sectional view, and FIG. 1B is a sidesectional view;

FIGS. 2A through 2D are enlarged views showing a shape of a plateaccording to the present invention, and FIGS. 2A through 2C are enlargedplan views of depressions, and FIG. 2D is an enlarged sectional view ofa heat exchange element;

FIGS. 3A and 3B are schematic views showing a structure of another heatexchange element according to the present invention, and FIG. 3A is aplan view, and FIG. 3B is a sectional view;

FIG. 4 is a schematic view showing a whole structure of an absorptionrefrigerating machine into which a heat exchanger of the presentinvention is incorporated;

FIG. 5 is a schematic view showing a whole structure of a plate typeheat exchanger according to a second embodiment of the presentinvention;

FIGS. 6A through 6D are schematic views explanatory of forming a plateaccording to the present invention, and FIG. 6A shows a state before aload is applied, FIG. 6B shows a state after a load is applied, FIG. 6Cis an enlarged view showing an example of a peripheral portion and anopening portion, and FIG. 6D is an enlarged view showing another exampleof a peripheral portion and an opening portion;

FIG. 7 is a vertical sectional view showing another heat exchangeelement used in the second embodiment of the present invention;

FIG. 8 is a schematic view showing a direction of plates when they arepiled on each other;

FIG. 9 is a plan view showing a structure of another plate used in thesecond embodiment of the present invention;

FIG. 10 is a schematic view showing a structure of the heat exchangeraccording to the second embodiment of the present invention which isused in a condenser of an absorption refrigerating machine;

FIG. 11 is a schematic view showing a construction of the heat exchangeraccording to the second embodiment of the present invention which isused in a regenerator of an absorption refrigerating machine;

FIG. 12 is a schematic view explanatory of a liquid flow of an externalfluid on a plate in a third embodiment of the present invention;

FIG. 13 is a partial enlarged view showing a liquid flow of an externalfluid on another plate in the third embodiment of the present invention;

FIGS. 14A and 14B are schematic views showing a whole structures ofanother plate type heat exchanger according to the third embodiment ofthe present invention, and FIG. 14A is a front sectional view, and FIG.14B is a side sectional view;

FIG. 15A is a front view showing a plate according to the thirdembodiment of the present invention, and FIG. 15B is a front viewshowing a conventional plate;

FIG. 16 is a sectional view showing a structure of a conventional heatexchanger;

FIG. 17 is an exploded perspective view showing a conventional plateexchanger; and

FIG. 18 is a schematic view explanatory of a liquid flow of an externalfluid on a conventional plate.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of a plate type heat exchanger according to the presentinvention will be described below in detail.

In a first embodiment of the present invention, two plates have aplurality of depressions, and the depressions are brought into contactwith and bonded to each other to form a space in the plates, so that thestrength of the plates is increased. The depressions prevent a flow of afluid flowing between the plates, for thereby improving heat transfer.Thus, a heat exchanger having high efficiency can be constructed withoutprovision of a turbulator (turbulence plate) conventionally insertedbetween the plates.

Next, the first embodiment of the present invention will be describedbelow with reference to the accompanying drawings.

FIGS. 1A and 1B are schematic views showing a whole structure of a platetype heat exchanger according to the first embodiment of the presentinvention, and FIG. 1A is a front sectional view, and FIG. 1B is a sidesectional view.

In FIGS. 1A and 1B, the reference numeral 1 denotes a plate, 2 a heatexchange element, 3 an external fluid introduction passage, 4 anexternal fluid discharge passage, 5 and 6 denote opening portions forintroducing and discharging an internal fluid, 7 a communicatingportion, and 9 a shell.

In the plate type heat exchanger shown in FIGS. 1A and 1B, eight heatexchange elements 2 composed of two plates 1 are housed in the shell 9.Four opening portions 5 and four opening portions 6 for introducing anddischarging internal fluid passages are respectively provided in theplate 1. The internal fluid is introduced into the plates through thefour opening portions 5 as the introduction passages, and is dischargedthrough the four opening portions 6 as the discharge passages.

On the other hand, the external fluid is introduced through the singleintroduction passage 3, passes over the outer surface of each of theplates, and is discharged through the single discharge passage 4. Thus,heat is exchanged between the internal fluid and the external fluid.

The shape of a hatching portion of the plate shown in FIG. 1B is shownas plan views in FIGS. 2A, 2B and 2C. FIG. 2D is an enlarged sectionalview of the heat exchange element 2.

As shown in FIGS. 2A through 2D, according to the present invention, theplate 1 has depressions 8 of a circular or elliptic shape, and thedepressions of the two plates are brought into contact with and bondedto each other to form the heat exchange element 2. Arrangement of thedepressions 8 formed in the plate 1 can be selected, as desired, inconnection with the strength of the plate. When the water pressure is490 kPa (5 kgf/cm²), the thickness of the plate is 0.3 to 0.5 mm, andthe size of a contacting portion is 0.3 mm, for example, the depressions8 may be arranged as follows:

In the case where the circular depressions are arranged in a checkeredpattern or a staggered pattern as shown in FIGS. 2A and 2B, it isdesirable that 0.5≦a/b≦2 and a×b≦250 mm².

In the case where the depressions have a horizontally elongated ellipticshape as shown in FIG. 2C, it is desirable that a ≧b/2, a≦20 mm. In thiscase, when a is close to 20 mm, the flat portion of the plate slightlyswells in use, which is acceptable for use.

In a peripheral portion of the heat exchange element 2, as shown in FIG.2D, the plate 1 is bent once, and the plate 1′ is bent twice, to thusform contact surfaces 10 and 11, which are inclined in parallel witheach other. In FIGS. 1A and 1B, the two plates are indicated by thereference numeral 1. In FIG. 2D, the two plates are distinguished fromeach other by the different reference numerals 1 and 1′. The depressionsformed in the respective plates 1 and 1′ are also distinguished fromeach other by the different reference numerals 8 and 8′. The plates 1,1′ are constructed so that the depressions 8, 8′ are brought intocontact with each other when the contact surfaces 10, 11 of the plates1, 1′ are piled on each other. The plates 1, 1′ having the same shape,except their peripheral portions, are piled on each other in oppositedirections.

At least one of the surfaces of the plates 1, 1′ is formed as aroughened surface to increase the wettability of the fluid involving aphase change on the plate surface. The two plates 1 and 1′ are piled oneach other, and the contacting portions of the depressions 8, 8′ and theperipheral portions 10, 11 are welded or brazed to be bonded to eachother, for thereby constituting the heat exchange element 2.

The communicating portions 7, 7′ of the heat exchange elements 2 arewelded or brazed to be bonded to each other to form the plate type heatexchanger. In the example shown in FIG. 1A, eight heat exchange elements2 are piled on and bonded to each other, and incorporated in the shell9.

FIGS. 3A and 3B show a structure of another heat exchange elementaccording to the present invention, and FIG. 3A is a plan view, and FIG.3B is a sectional view. In the example shown in FIGS. 3A and 3B, a largenumber of opening portions 5, 6 of the plate are provided in a staggeredpattern. The pattern shown in FIGS. 2A through 2C may be applied to ahatching portion shown in FIG. 3A.

FIG. 4 is a schematic view showing an example of using an absorptionrefrigerating machine into which a heat exchanger according to thepresent invention is incorporated. In this example, the heat exchangeelement 2 shown in FIGS. 3A and 3B is incorporated into each of anabsorber A, a condenser C, a generator G, and an evaporator E. In theabsorption refrigerating machine, as an internal fluid for the heatexchange element 2, cooling water flows in the absorber A and thecondenser C, a heating medium flows in the generator G, and chilledwater flows in the evaporator E. In the absorber A, a concentratedsolution as an external fluid is cooled and absorbs a refrigerant fromthe evaporator E. In the generator G, a dilute solution as an externalfluid is heated to evaporate the refrigerant and changes into aconcentrated solution. In the condenser C, a refrigerant vapor from thegenerator G is cooled to form a refrigerant liquid. In the evaporator E,the refrigerant liquid is evaporated to form a refrigerant vapor.

The absorption refrigerating machine shown in FIG. 4 will be describedbelow. In the absorber A, a concentrated solution absorbs a refrigerantvapor evaporated in the evaporator E to change into a dilute solution.The dilute solution is passed through a passage 101 and a heated side ofa solution heat exchanger SH, and then introduced into the generator Gvia a passage 102 by a solution pump SP. The dilute solution introducedinto the generator G is heated by a heat source 112 to evaporate therefrigerant, so that the dilute solution changes into a concentratedsolution. The concentrated solution is passed through a passage 113 andthe heating side of the solution heat exchanger SH, and then introducedvia a passage 114 into the absorber A, where the concentrated solutionabsorbs a refrigerant vapor again to change into a dilute solution.Thus, the solution is circulated.

On the other hand, the refrigerant is evaporated in the generator G tobecome a refrigerant vapor. The refrigerant vapor reaches the condenserC, where the refrigerant vapor is condensed into a refrigerant liquid,which is introduced into the evaporator E via a passage 105. While theintroduced refrigerant liquid is circulated into the evaporator E via apassage 106 by the refrigerant pump FP, the refrigerant liquid isevaporated in the evaporator E for cooling chilled water 111. Theevaporated refrigerant reaches the absorber A, where the refrigerant isabsorbed into the concentrated solution. The absorbed refrigerantreaches the generator G, where the refrigerant is evaporated. Thus, therefrigerant is circulated.

The cooling water is introduced through a passage 107 and branched intoa flow through a passage 108 and a flow through a passage 109. Theseflows are respectively introduced into the absorber A and the condenserC and discharged through a passage 110.

According to the first aspect of the present invention, since thedepressions of the plates are brought into contact with and bonded toeach other, the strength of the plates is increased, and a flow of afluid flowing between the plates can simultaneously be disturbed. Hence,since there is no need to insert a turbulator (turbulence plate) betweenthe plates, the number of required components can be decreased, and thecost of production and assembly can be reduced. Further, a plate typeheat exchanger according to the present invention has a highly efficientfunction of heat exchange.

Furthermore, since the peripheral portions of the two plates are broughtinto contact with each other along the whole peripheries, the cost ofassembly can be reduced. Besides, since the plate type heat exchangerhas a plurality of the opening portions in the plates, the heatexchanger can be constructed so that the internal fluid can flow inlarge quantities and the flow of the external fluid is not disturbed.

Next, a second embodiment of a plate type heat exchanger according tothe present invention will be described below with reference to theaccompanying drawings.

In the second embodiment of the present invention, plates have a shapesuitable for meeting the following conditions: two plates havingprojections and depressions are piled on each other to form a spacetherebetween. When the peripheral portions and the opening portions(inlet and outlet for fluids) at both sides of the two plates are simplypiled, the plates are brought into light contact (i.e., line contact)with each other along the whole peripheries. When a force in a directionof piling is increased, the contacting portions are changed in shape tobe brought into surface contact with each other. When the force isincreased until the projections and depressions of the respective platesare brought into contact with each other, the area of the contactsurface is increased, and hence the peripheries of the plates can besealed by brazing.

In the case of brazing, plates are brazed while a force is being appliedin order to bring the plates into close contact with each other.Accordingly, the aforementioned plates are preferable because, uponapplication of this force, the peripheral portions of the plates becomeparallel, and further the projections and depressions of the plates arebrought into contact with each other.

When the two plates described above are piled on each other while abrazing filler metal is laid (applied) at portions to be brought intocontact with each other, a heat exchange element which has a fluidpassage between the opening portions formed at both ends of the platesand the aforementioned space is formed. A desired number of heatexchange elements are piled on each other so that the opening portionscommunicate with each other among the heat exchange elements. The heatexchange elements are brazed in such a state that a force is beingapplied in a direction of piling. Consequently, the heat exchangeelements are brought into contact with each other at a time, so that aplate type heat exchanger according to the present invention can bemanufactured.

With the above arrangement, the projections and depressions of the platecan be formed as a curved pattern inside and outside heat exchangeelements constituted by one type of plates (or two types of plates), andhence the heat exchanger has a highly efficient function of heatexchange.

The present invention can be applied to not only a case of brazing, butalso a case where a gasket is interposed between the plates and a forceis applied from the outside, and a case where the plates are sealed bywelding.

In the case of welding or brazing, the plates are piled on and connectedto each other while a force is being applied in a direction of piling.If the peripheral portions of the plates are in parallel with each otherat a free state, then the applied force is likely to open the peripheralportions. Particularly in the case of brazing, the strength of theperipheral portions is extremely lowered.

When the plates are piled on each other while a brazing filler metal islaid between contacting portions and/or contact surfaces. The plates areheated in a furnace while a force is being applied in a direction ofpiling (a weight is being loaded on the plates), to be brazed at a time.Thus, the heat exchange structure is manufactured by one step, and theoperation process can remarkably be simplified.

The projections and depressions of the plate according to the presentinvention can be formed as a corrugated pattern extending in apredetermined direction, and hence a complicated passage curvedtwo-dimensionally can be formed with a relatively simple arrangement.

Further, the plate may have spot-like projections and depressions havinga cross section of a circular shape or the like. When such plates arepiled on each other, the size of the outer space and the size of theinner space can be changed to cope with an extremely low-pressure vapor.

Furthermore, one of the opening portions at both ends of the plate isprovided with a rising portion, so that positioning of the plates uponpiling can be facilitated by the fitting of the opening portions. Thus,the two-dimensional positioning of the plates can naturally be performedby simply piling the plates on each other. Consequently, themanufacturing process can be simplified.

Next, the second embodiment of the present invention will be describedbelow with reference to the accompanying drawings.

FIG. 5 is a sectional view showing a whole structure of a plate typeheat exchanger according to the second embodiment of the presentinvention. As shown in FIG. 5, the plate type heat exchanger isconstituted by mounting a heat exchange structure 30, which comprisesthree heat exchange elements 12 bonded to each other, in a shell 9extending in a longitudinal direction.

In the heat exchange element 12, as shown in FIG. 6A, when two plates 14having projections and depressions in a corrugated pattern arespontaneously piled on each other, the peripheral contacting portionsare brought into line contact with each other along the wholeperipheries. On the other hand, an opening portion 17 is brought intoline contact with an opening contacting portion 16 a of an adjacent heatexchange element 12′. When a force (normally, a weight) is applied in adirection of piling, a space R1 is formed as a result of contact betweenthe projections and depressions in the corrugated patterns, and theperipheral portions deform to be brought into surface contact with eachother, as shown in FIG. 6B. The opening portions also deform such thatthe contacting portions 16 a are brought into surface contact with eachother. At this time, if the projections of the heat exchange element 12are brought into contact with contacting portions 20 of the adjacentheat exchange element 12′, then the heat exchange elements 12, 12′ canbe bonded to each other by brazing.

The projection-depression pattern may be a pattern suitable forappropriately disturbing the internal and external passages and ensuringstrength, such as a corrugated pattern close to a sine wave as shown inFIG. 6A, or a pattern of circular protrusions as shown in FIG. 7.

The corrugated pattern is inclined at a predetermined angle θ to alongitudinal direction as shown in FIG. 8. Such plates 14 arealternately disposed in reverse directions so that the corrugatedpatterns cross each other.

Therefore, in the upper and lower plates 14, contacting portions 15 areformed at positions at which ridgelines of the corrugated patternsintersect in a mesh pattern, as shown in FIGS. 6A and 6B, so that curvedpassages are formed in the internal space R1.

Truncated conical protuberances 16 are formed at both end of the plate14. The contacting portion 16 a at the upper end of the protuberance 16has an inclination angle of β=about 1° to about 8° to the horizontaldirection as shown in FIG. 6C. This contacting portion 16 a is flattenedwhen the heat exchange elements are piled on each other and a force isapplied. The opening portion 17 is formed at the contacting portion 16a. As shown in FIG. 6D, a rising portion 18 is provided in one of theopening portions at both ends. When the rising portion 18 of the heatexchange element 12 is fitted into the opening portion of the adjacentheat exchange element 12′ upon piling, positioning of the heat exchangeelements upon piling can be facilitated. As shown in FIG. 9, theprotuberance 16 and the opening portion 17 may have a rectangular shape,rather than a circular shape.

As shown in FIG. 6C, a peripheral contacting portion 19 of the plate 14has an inclined surface. Thus, the peripheral contacting portions 19 arebrought into line contact with each other when the heat exchangeelements are faced to and piled on each other, and deform to be broughtinto surface contact with each other when a force is applied. Theinclination of the peripheral contacting portion 19 is at an angle ofα=about 1° to about 8°. When the heat exchange elements are piled oneach other and a force is applied so that the contact portions 19 arebrought into surface contact with each other, projection-depressionpatterns are brought into contact with each other, as shown in FIG. 6B.The plates 14 having the same shape are piled on each other in reversedirections.

In order to facilitate positioning when the heat exchange elements arefaced to and piled on each other, projections and depressions, orprotrusions 31 and notches 32 for engagement may be provided at severalpositions of the peripheral portion, as shown in FIG. 9.

The two plates 14 are piled on each other, and the contacting portions15 of the projection-depression patterns and the peripheral portions 19are welded or brazed to be bonded to each other, for thereby forming theheat exchange element 2.

In the example shown in FIG. 5, the heat exchange structure 30 isconstituted by the three heat exchange elements 12 piled on each other,and the contacting portions 16 a of the protuberances 16 are bonded toeach other by welding or brazing, for thereby forming the heat exchangestructure 30. As a result, a passage communicating with the space insidethe shell is formed between the heat exchange elements 12.

As shown in FIG. 5, a shut-off plate 21 is secured to the openingportion 17 of the heat exchange element 12 on one side of the adjacentheat exchange elements 12 to close the opening portion 17. A pipe 22 forsupplying the first heat exchange fluid into and discharging the firstheat exchange fluid from the internal spaces R1 of the heat exchangeelements 12 is connected to the opening portion 17 of the heat exchangeelement 12 on the other side. The end plate may have neither a shut-offplate 21 nor an opening portion 17. Through-holes 23 for disposing thepipes 22 are formed in the shell 9, and pipes 24 for supplying thesecond fluid into and discharging the second fluid from the space R2 inthe shell are formed on walls on both sides in the longitudinaldirection of the shell.

Particularly, if the truncated conical protuberance 16 has the sameheight as the corrugated projection and depression pattern, thecontacting portions 20 of the adjacent heat exchange elements 12 and thecontacting portions 16 a of the protuberances 16 of the adjacent heatexchange elements 12 are welded or brazed to be bonded to each other,for thereby forming the heat exchange structure 30. Thus, the structuralstrength is further increased, and curved passages for communicating aspace inside the shell are formed between the heat exchange elements 12,thereby increasing efficient function of heat exchange.

To manufacture such a plate type heat exchanger, the two plates 14 maybe welded to form the heat exchange element 12, and the heat exchangeelements 12 may be piled on each other and welded to form the heatexchange structure 30. In a simpler method, six plates 14 are piled oneach other with a brazing filler metal interposed between the peripheralportions 19, between the contacting portions 16a of the openingportions, and between the contacting portions 15, 20 of the corrugatedpatterns, and heated in a furnace. In this manner, the heat exchangestructure 30 can easily be manufactured by one step, and can bemanufactured in large quantities depending on the capacity of thefurnace.

As shown in FIG. 6D, one of the opening portions in the plate 14 may beprovided with the rising portion to fit the rising portion into theopening portion of he adjacent heat exchange element. In addition, asshown in FIG. 9, protrusions 31 and notches 32 for engagement may beprovided at several positions of the peripheral portion. Thus, when oneheat exchange element is placed on another heat exchange element, theplates 14 are spontaneously positioned and stably supported by theprotrusions 31 and the notches 32, for thereby further facilitating theaforementioned manufacturing process.

A brazing filler metal may be laid between the contacting portions 15,20, between the peripheral portions 19, and at other necessarypositions, as well as the heat exchange structure 30, and the plates 14,the shell 9, the pipes 22, 24, and the shut-off plate 21 are assembledand heated in the furnace to be brazed. Thus, the entire heat exchangerincluding the shell 9 can be manufactured at a time.

In the plate type heat exchanger thus formed, the first and secondfluids are supplied to the supply and discharge pipe 22, 24 to performheat exchange. When the fluid involving a phase change as a result ofheat exchange, or low-pressure refrigerant vapor is supplied to thebroader internal space R2 in the shell 9, the flows are smoothened. Thefirst fluid flows through the passages in the heat exchange elements 12,as indicated by arrows A in FIG. 5. The second fluid flows through thepassages formed between the heat exchange elements 12 or between theheat exchange elements 12 and the shell 9, as indicated by arrows B.

As described above, the corrugated patterns are formed in the plates 14dividing the passages. Further, the corrugated patterns are inclined ata predetermined angle θ to the main direction of the flow between theopening portions 17. Thus, the passages are complicated such that thepassages are curved upward, downward, rightward, and leftward.Therefore, the flow near the surface of the plate 14 becomes a turbulentflow, so that heat is efficiently exchanged between the flow and theplate 14.

Moreover, the projections and depressions formed in the plate 14 areformed in a corrugated pattern, and the corrugated patterns intersect ata predetermined angle. Thus, the intersections of the checkeredridgeline constitute the contacting portions 15, 20, which are arrangedequally on the surfaces of the plates 14. This is preferred for thestrength of the heat exchange structure 30.

It is advantageous from the viewpoint of heat transfer and strength thatthe shape of the projection-depression pattern of the plate is formed ina corrugated pattern close to a sine wave as shown in FIG. 6A. However,depending on the viscosity and phase change characteristics of the heatexchange fluid used, the projection-depression pattern may be a patternof circular protrusions as shown in FIG. 7, or another shape may beselected as desired. The circular protrusions shown in FIG. 7 can bechanged in height by the projections and depressions, for therebychanging the sizes of the spaces R1 and R2.

Projections may further be provided in the projections of the corrugatedpattern at suitable intervals, so that the space between the adjacentelements (i.e., space R2) can be ensured between the protrusions andbetween the opening portions 16 a.

The plate type heat exchanger according to the present invention can beapplied to a condenser, a regenerator, an absorber, and an evaporator ofan absorption refrigerating machine. In the case of a condenser, forexample, as shown in a schematic structural view in FIG. 10, coolingwater 25 is flowed through the R1 side, and a refrigerant vapor 26 fromthe regenerator is introduced into the R2 side from an upper portion andwithdrawn as a refrigerant liquid 27 from a lower portion.

In the case of a regenerator, as shown in a schematic structural view inFIG. 11, a heat source fluid 27 (hot water or vapor in a single effectabsorption refrigerating machine, or a refrigerant vapor from ahigh-temperature regenerator in a multiple effect absorptionrefrigerating machine) is introduced into R1, a dilute solution 28 isintroduced into R2, and the refrigerant 26 is generated from an upperportion of the heat exchanger. The reference numeral 29 denotes aconcentrated solution. When vapor is used in the R1 side, it isdesirable that the opening portion is formed in a rectangular shapespreading over the entire width as shown in FIG. 9 to facilitatedischarge of the condensate.

According to the second embodiment of the present invention, projectionsand depressions of plates can form curved passages inside and outsideheat exchange elements constituted by one type of plates or two types ofplates. Hence, a heat exchanger having a highly efficient function ofheat exchange can be manufactured at low cost by a small number ofcomponents and a simple manufacturing process.

Further, the contacting portions of the projections and depressions arebonded to each other, for thereby increasing the strength. Furthermore,the projections and depressions are formed at certain intervals toperform heat exchange uniformly. Thus, a heat exchanger having a highlyefficient function of heat exchange without thermal deformation can bemanufactured.

Particularly, the projections and depressions are formed in a corrugatedpattern. Hence, a heat exchanger having a highly efficient function ofheat exchange in which complicated passages curved two-dimensionally areformed with a relatively simple arrangement can be provided at low cost.Further, the plates are constituted such that a brazing filler metal islaid between folded peripheral portions of the adjacent plates, and theperipheral portions have parallel contact surfaces when a force forbrazing is applied, and the plates are bonded to each other by brazing.In this manner, firm and leakless bonding is carried out at low cost bya relatively simple working process. In this case, the use of so-calledfurnace brazing can remarkably simplify the work process and can reducethe cost.

Next, a third embodiment of the present invention will be describedbelow with reference to the accompanying drawings.

The entire structure of a plate type heat exchanger according to thethird embodiment of the present invention is the same as that of theplate type heat exchanger shown in FIGS. 1A and 1B, and hence will notbe described.

FIG. 12 is a schematic view explanatory of a liquid flow on a surface ofa plate when an external fluid is sprayed on the plate in the plate typeheat exchanger shown in FIGS. 1A and 1B. In FIG. 12, a hatched arearepresents regions of the liquid flow, and a liquid does not flow in aportion a below the opening portion (supply passage) 5, 6 withouthatching. FIG. 13 is a partial enlarged view showing a plate in anotherexample. In FIG. 13, the reference numeral 38 denotes a flow of anexternal fluid.

According to the present invention, as described above, at least one ofthe inlet and the outlet for an internal fluid comprises a plurality ofsupply passages 5, 6, and the internal fluid is supplied through thesupply passages. Accordingly, compared with a conventional plate typeheat exchanger, the size of the individual supply passage can be madesmall. Therefore, even at a high flow rate, the flow 38 of the externalfluid is likely not to be prevented, and the liquid can easily flowwithin the portion below the supply passage, so that the heat transfersurface can effectively be used. Since the internal fluid is suppliedthrough a plurality of supply passages, the internal flow becomesuniform, for thereby improving the performance of heat transfer. Liquiddistributing portions around the ports can be made small, and the heattransfer area can be enlarged.

Even when the flow rate is increased, the number of supply passages isincreased to cope with the increased flow rate.

Further, the supply passage can be designed so as to have moderate flowcontrollability. Therefore, as shown in FIG. 13, the supply passages arearranged laterally side by side in an upper portion of the heatexchanger, whereby the supply passages themselves can be used so as toserve as liquid distributors for the external fluid. A cylinder or acircular tube, which can be easily produced and processed, can be usedfor the supply passage. A turbulator (turbulence plate) may be insertedbetween the plates so that the external fluid generates the turbulenceto flow uniformly, for thereby further improving the efficiency of heatexchange.

FIGS. 14A and 14B are schematic views showing a whole structure ofanother plate type heat exchanger according to the third embodiment ofthe present invention, and FIG. 14A is a front sectional view, and FIG.14B is a side sectional view.

In FIGS. 14A and 14B, the respective reference numerals denote the samecomponents as those shown in FIGS. 1A and 1B. In FIGS. 14A and 14B, anopening portion 5 constituting an internal fluid introduction passage(supply passage), and an opening portion 6 constituting a dischargepassage (supply passage) are introduced into a shell 9 as a single tube,and connected to respective plates 1 through a plurality of internalfluid connecting tubes 7 in the shell. Thus, the internal fluid passagesmay be provided in a vertical direction, and comprise a plurality ofpassages in the shell.

In order to clarify the difference between the plate of the heatexchanger according to the present invention and the plate of theconventional heat exchanger, a front view of the plate according to thepresent invention is shown in FIG. 15A, and a front view of theconventional plate is shown in FIG. 15B.

According to the third embodiment of the present invention, the effectsenumerated below can be obtained.

(1) An internal fluid at a high flow rate can be flowed.

(2) The flow of an external fluid is likely not to be prevented.

(3) A heat exchanger can be manufactured at low cost without complicatedprocesses.

(4) The ports and the distributing portions can be made small, and hencethe heat transfer area can be widened.

(5) The performance of heat transfer of the heat exchanger can beimproved by using the supply passages as liquid distributors.

INDUSTRIAL APPLICABILITY

The present invention relates to a plate type heat exchanger forexchanging heat between two fluids flowing alternately through adjacentfluid passages between piled plates. The present invention can be usedin an evaporator of a refrigerator, and an evaporator, a condenser, aregenerator, and an absorber of an absorption refrigerating machine.

What is claimed is:
 1. A plate type heat exchanger having a shellcontaining a plurality of heat exchange elements, each of said heatexchange elements being composed of two plates for exchanging heatbetween an internal fluid flowing inside said heat exchange element andan external fluid flowing outside said heat exchange elementcharacterized in that: peripheral portions of said two plates beingsealedly connected together to form an internal space in which saidinternal fluid flows and an external space in which said external fluidflows; an introduction passage and a discharge passage being connectedto said plates and communicating with said internal space for allowingsaid internal fluid to flow inside said two plates; and an introductionpassage and a discharge passage being connected to said shell andcommunicating with an interior of said shell for allowing said externalfluid to flow as a liquid film on surfaces of said plates within a spacebetween the outside of said plates and said shell, wherein at least oneof said introduction passage and said discharge passage for saidinternal fluid connected to each of said plates comprises a plurality ofpassages, and said passages including a sprayer provided above the heatexchange elements for spraying said external fluid on said plates toform a liquid film on the surfaces of said plates.
 2. A refrigeratingmachine comprising said plate type heat exchanger according to claim 1as at least one of an evaporator, an absorber, a regenerator, and acondenser.
 3. A plate type heat exchanger according to claim 1, whereinsaid two plates have a plurality of depressions, and said depressionsare brought into contact with and bonded to each other at contactingportions defined by said depressions, said depressions of said platesare each formed in a circular shape, or a horizontally elongatedelliptic shape, and said contacting portions between said depressionseach having a plane surface of at least 0.3 mm in width.
 4. A plate typeheat exchanger according to claim 3, wherein said peripheral portions ofsaid two plates are brought into contact with each other along the wholeperipheries of said plates upon piling, and contacting portions betweensaid peripheral portions are sealed by bonding.
 5. A plate type heatexchanger according to claim 1, wherein said heat exchange element hasopening portions at both ends thereof, at least one of said openingportions is composed of a plurality of openings.
 6. A plate type heatexchanger according to claim 3, wherein said heat exchange element hasopening portions at both ends thereof, said plates of each heat exchangeelement are integrated by brazing said contacting portions at saidperipheral portion and at said opening portions of said plates.
 7. Aplate type heat exchanger according to claim 1, wherein said two plateshave projections and depressions formed in a shape inclined to onedirection.
 8. A plate type heat exchanger according to claim 1, whereinsaid two plates have projections and depressions formed as spot-likeprojections and depressions having a circular or other cross section,and the height of said projections is larger than the depth of saiddepressions when said heat exchange element is constituted.
 9. A platetype heat exchanger according to claim 1, wherein each said plate has anopening portion containing a rising portion so that said rising portionis fitted into an opening portion of another plate when said plates arepiled on each other.